Re: shapes-ISSUE-40 (Property Cardinality): sh:min/max constrains properties, not values

Oh, now I think I get it. Holger, you are describing this in terms of 
the result of a SPARQL query, right? You query on the property, and 
count the number of objects that are returned? and that tells you how 
many triples with that property exist?

That is probably what confused me, because it isn't clear from the 
language that a query is assumed. I'll let others weigh in, but I would 
rather that we not assume query functionality, so I'd go for "count the 
number of triples with the focus node as the subject and the given 
property as the predicate."

kc

On 4/6/15 8:20 PM, Karen Coyle wrote:
>
>
> On 4/6/15 7:00 PM, Holger Knublauch wrote:
>> I have attempted to clarify this via
>>
>> https://github.com/w3c/data-shapes/commit/1ffa8cd3225d2cc340ae3883abd5411913d7a7d4
>>
>>
>>
>> Please let me know if this helps. I had started to use the term "value"
>> because I thought that "object" is less clear to newcomers who are not
>> too familiar with RDF technology. Yet for a formal spec, using the term
>> "object" may indeed be less objectionable.
>
> Sorry, Holger, trading "object" for "value" doesn't help -- my confusion
> was something else.
>
> What exactly is being constrained in:
>
> "The properties sh:minCount and sh:maxCount restrict the number of
> objects in triples with the focus node as the subject and the given
> property as the predicate"
>
> I think what you are saying is that you are restricting the number of
> times a particular predicate can appear in the focus node. Right?
> Because this is listed as a property constraint. Where do the objects
> come into that if this is a constraint on the propert(y/ies)? It's the
> "objects in triples" that throws me off -- number of objects in a triple
> is 1, right? So clearly I'm not reading this with the meaning you intend
> to convey.
>
> kc
>
>>
>> Holger
>>
>>
>> On 4/6/2015 2:08, RDF Data Shapes Working Group Issue Tracker wrote:
>>> shapes-ISSUE-40 (Property Cardinality): sh:min/max constrains
>>> properties, not values
>>>
>>> http://www.w3.org/2014/data-shapes/track/issues/40
>>>
>>> Raised by: Karen Coyle
>>> On product:
>>>
>>> The spec at https://w3c.github.io/data-shapes/shacl/ currently reads:
>>>
>>> "The properties sh:minCount and sh:maxCount restrict the number of
>>> values of the given property at the focus node."
>>>
>>> It should read:
>>> "The properties sh:minCount and sh:maxCount restrict the cardinality
>>> of properties of the focus node."
>>>
>>> The cardinality of the value of a triple is always min=1 max=1. It is
>>> the cardinality of the properties in the node that can be constrained,
>>> e.g.
>>>
>>> sh:property [
>>>         sh:predicate foaf:name ;
>>>         sh:minCount 1 ;
>>>         sh:maxCount 1 .
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600

Received on Tuesday, 7 April 2015 03:59:31 UTC